As Steven Pinker convincingly explains in 'How the mind works', happiness, laughter, grief and other emotions are expressed facially thru' involuntarily controlled muscles. Laughter is a way of cementing friendships (you can't fake laughter well if the muscles that control genuine laughter are involuntary). Or maybe laughter has extra-terrestrial origins and this is all one big experiment for some bugs from mars (read that in an Asimov, I think).
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As Steven Pinker convincingly explains in 'How the mind works', happiness, laughter, grief and other emotions are expressed facially thru' involuntarily controlled muscles. Laughter is a way of cementing friendships (you can't fake laughter well if the muscles that control genuine laughter are involuntary).
Or maybe laughter has extra-terrestrial origins and this is all one big experiment for some bugs from mars (read that in an Asimov, I think).